A connecting device is well known from EP 1 217 284 B1. The connecting device has a connection piece in which a valve body is integrated. The valve body seals off the connection piece in the unloaded initial state and is embodied in a cup-like and resiliently flexible manner. The valve body is produced in one piece from an elastomer material. A top region of the valve body is provided with a slit arrangement which widens in the event of elastic deformation of the valve body and thus allows throughflow through the valve body. Elastic deformation of the valve body occurs when the connection piece is connected to a further functional part of the medical infusion system, in particular an infusion syringe, a hose system or the like.
EP 1 470 352 B1 shows a further connecting device for a medical infusion system, in which an elastically deformable valve body is likewise integrated in a connection piece, said valve body being formed in a cup-like manner and having an openable slit arrangement in a cap-shaped top region.
A further connecting device is known from WO 2013/017698 A1. The known connecting device has a connection piece which is provided with Luer profiles in order to allow the connection of a functional part, provided with a complementary Luer connector, of the medical infusion system. Integrated in the connection piece, in order to seal off an opening in the connection piece, is a cup-like valve body, which is produced integrally from an elastically deformable material. The valve body expands substantially continuously from a cap-shaped top region to a base ring, with the result that the valve body has a bell shape. The valve body is provided with a slit arrangement in its top region in the same way as is the case in the valve bodies of the previously described connecting devices.